EXPLANATION ©OF PLATE Vil: 
LAMELLIBRANCH MOLLUSCS OF SEISTAN AND THE AFGHAN 
DESERT. 
Corbicula fluminalis (Miller). 
Fics. I1-6.—A series of shells from the edge of the Helmand 
in the Afghan desert, illustrating variation in 
form and size. 
Lamellidens marginalis, subsp. rhadinaeus, subsp. nov. 
Fic. 7.—Type-specimen (phase A) from the desert near Nas- 
ratabad, Seistan. 
Fics. 8-11.—A series of shells of different ages from the 
Hamun-i-Helmand near Lab-i-Baring. 
All the shells are shown of the natural size. 
